He wouldn't say that in public because it would be harmful to the Scala community, but everyone who read it is very glad for having read it.
But if everyone thinks this way, those innovations will have one view on the web (where there is an image to care for) and another one of engineering departments, where people get real... and that sucks.
I think his point was that the original email was very particular to his use, and it might not have the same issues used by different people. So his public opinion of Scala wouldn't be him lying, it would be him generalizing it more. He was asked what the problems were so he answered. If it was a general post about the language, more care would have probably been given to point out both the negatives and positives. My .02 on how I read the various posts.
Obviously he took the time to write this post in such detail because he hopes that its intended recipients can take action to address the issues he raises.
It's not like there isn't already plenty of Scala bashing going around these days anyway.
But if everyone thinks this way, those innovations will have one view on the web (where there is an image to care for) and another one of engineering departments, where people get real... and that sucks.